Method of making plastics



April 3, 1945. J. c. B OYD 2,372,761 METJiOD OF MAKING PLASTICS. u

' Filed Sept. 15, 1941 mill/III WW:

I N VENTOR \JOHNI.BOYD

'BYM'AMuQ LL A TTOHNEYS the-material being treated.

Patented Apr. 3, l9 45 ff tn-Juno OF MAKING rms'i'ros We 1' John). Moi.

t I 5 ,a u uo s i mmis, 1941, Serial no. 410,882

plastic materials. 1-, In.-.particular, itrelates to a 1 surface treatment'method bymeans of. which certain unusual and desirable appearance effects as well as other. surface-characteristics may be obtained. j K

Briefly, the invention comprises a heat treata ment that may be effected, for example, by a flame or by hot air directed upon the .surface of certain' plastic materials, which treatment results in various color efiects', texture effects, and degrees of translucency or opacity on the surface treated,

these efiects and degrees of translucency being controlledhy and dependent upon the contour of the surface treated, the manner of application of the treatment, and the color and composition of It is an object of the invention to provide a method for obtaining-a plastic material, having one or more of the following characteristics, to-

\ r -7Claims. (0141-17). This invention relates tea method of treating Fig. 5 is'asection onthe line 55 of Fig. 4;

Fig. 6- is aview 'of a different piece of material formed of two separate pieces; and

Fig. 7 is a section" on the line of Fig. 6. The ornamentof Figs. land 2 is shown in Fig. 1 as having a main body portion l0 consisting of a figure holding a'bow H. In this case the surface of the figure is irregular to correspond with the various irregularities of the human form. The body of this ornament is made of a plastic material which is entirely translucent prior to .treatment and is of the color of whatever dye is used in the material. The bow ll, however, is made of a plastic material which is entirely opaque prior to treatment. The how I I also may be made of a plastic of contrasting color to that 1 used for the other parts of the ornament.

wit: gradation of color, gradation of color brilliance or shade, gradation. of translucency, contrast of color, contrast of color brilliance or shade, contrasting degrees of translucency, opacity,

opacity at some points and translucency at others, attractiveness of surface texture, a surface that due to its texture appearance does not readily show scratches.

More specifically, it' is an object or the invention to produce upon a more or less translucent plastic material of one or more basiccolors a surface that is at least in part opaque or tends toward opacity, and especially a surface that, though itretains its original color hue, tends toward whiteness where it is opaque or where it v tends toward opacity. also, it is-an object of the invention to produceupou an opaque plastic material of one'for more basic colors a' surface that in part or' throughout tends toward whiteness while still retaining its original color line.

It is anjobject of the' 'invention to provide a method for producing a. texture of surface on- After the treatment to be described, the body I0 achieves, upon the upstanding or raised portions l2 of its surface, a lighter coloration tendin-g somewhat toward white but still similar in color hue to the untreated material and in the deeper parts or declivities l3 upon the surface it retains a greater or lesser, and usually graduated,

degree of its original translucency and darker coloration.

The bow ll, prior to the surface treatment of the material, is opaque and of the color of whatever dye is used in it. After the treatment to be described the figure ll'remains opaque throughout-and achieves a lighter coloration similar inhue to the untreated material but tending somewhat toward white.

In the ornament of Figs. 3,-4, and 5 the device is shown as a disc 20 having a main raised surface 2|,- with indented portions 22 therein, here represented as footprints.-

Before the treatment the whole ohject is translucent- After the treatment, the surface portion 2| becomes opaque, and whitish, but tinted with I the original color. The treatment does not affect plastic material of the nature of a fused surface,

especially where themainbody of the, material one that does notfshow scratching. Inthe drawing has a more-crystalline aspect, and'-particularly Fig. 1 is a view of an ornament prior to the' surface treatment; 1 I I V t Fig. 2 is a view of the ornament after the surface. treatment; Fig. 3 is a view of another ornament prior to the surface treatment:

Fig. 4 is a similar view. of the ornament in a Fig. 3 after the surface treatment:

the indentations 22, so that the appearance'is of dark and translucent footprints contrasted with 7 .alighterand opaque surface- .In Fig. 5 the stir-I face portion after the treatment is indicated by the portion 23, somewhat exaggerated as to thick ness. Actually, the surface portion probably ex,

tends somewhat irregularly into the material, too.

It may be-noted that in Fig. 5 the back is'translucent, as it is not treated. Therefore, if light is directedag'ainst the back of this object it will shine throughonly where the front is untreated and'therefore translucent. By this method at-l tractive and colorfulilluminated signs and dis "-0 play-pieces may be produced. Likewise illumination may be used to secure attractive effects with figures produced by the techniques illustrated in Figs. 2 and 'I.

In the design shown in Figs. 6 and 7, there is shown a first portion 30 of a plastic of predetermined color superimposed over which is 'an additional layer 3| of a different, and preferably lighter color of plastic material, such as the whitish translucent plastic familiar in, the art. After the treatment has been applied to the upper surface of the portion 3| and to a varying degree to the V-shaped groove-that is, more at the unmelted or fused portions of the surface retain their and translucent quality, I

If the dye color is added to the powder solvent mixture and subsequently the material is fused or melted at the surface, then the result is simithe higher portion of the groove, less at the medium high portions of the groove and none at the bottom portions of the groove-the result is that the color of the lower or first piece of plastic shows through with varying intensity deter- .mined by the degree of translucency at each point on the surface of the upper portion 3|. The degree of translucency is a function of the thickness lar to the above and the fused or melted surfaces have an opaque and whitish'appearances but still retain the color hue of the dyecolor used.

In an ornament such as in Fig. 2the effect is that of a patina. In Fig. 4. the effect is simp two contrasting surfaces. The type of Fig. 4 may be used for lettering with-the result of having either. the letters themselves cutinto'the 'background, or the background cut away from the letters, so that the letters stand out by contrast' in color. I

of the portion 3| and of the extent of the surface treatment producing the opaque or partially opaque parts 32. Thus, it will not show through on surface 32 and will show through with greater intensity at the bottom of the V wedge 33 and with lesser intensity toward the top part of V wedge 33.

The method of attaining the foregoing surface effects involves the use of plastic materials which are molded by one of the known methods, particularly where there is present within the material or on its surface some material such as one of the solvents used in connection with the plaseight hours, under ordinary atmospheric conditions, it will become hard to the touch. At this time of later it is best to make theheat application to the surface. Heat application is then made to the surface, as by a-flame or by heated air, or

other means, until the surface is melted or fused.

If a flame is used a clean flame is preferable, such as that produced by. gas or alcohol, as it does not produce deposits of foreign matter. Any solvent or other volatile matter that might be present on the surface tends to burn away with the application of the name or heated air. However, the heat applied is not great enough, during the short period of application; to burn or destroy the basic plastic at the'sm-face but rather thebasic plastic at thesu-rfac'e is fused or melted to some extent. The melting or fusing occurs o he more exposed surfaces sooner-than it does on the surfaces that are below the level of these more exposed surfaces. The plastic object may be with- 135' drawn from the flame" or heat in such time as to leave the proper portions of the surface such as i3, 22, or 33 unaffected, and to limit thexesult to a melting and fusing of the materials at the surface, rather than burning them by complete combustion. The end point of the melting or fusing may be recognized by observing the appearance of the surface of the material. 7 It is noted that the melted or fused surfaces polishing, and for some purposes it is In order to achieve a highly polished. surface, a slight abrasion is performed on the treated por tion, and then a polish may be added by a waxedwheel, tumbling barrel, or similar polishing means. The addition of a lacquer applied before" polishing gives a very highly polished eflech; Polishing without the abrasion gives a more I rugged appearance. Another effect may be produced by abrasions without either lacquering or to abrade, polish, or lacquer.

In the foregoing method, the shading and patina effect may be obtained, two-toned effects Y may be obtained, and lettering which contrasts in color with its background may be produced. Figures and characters may be embodied into the surface, both in the positive and the negative.

Another effect may be obtained by retarding the flame or heated air from certain parts-of the surface and app ying the process to other parts,

as by directing the flame, which method produces an effect such as thatof cluds onthe surface of the material. This may also be accomplished by masking out certain parts, designs, or figures with a nonburning material.

It is not definitely known that chemical changes take place during the process. The'basic plastic material is at the start granular in the sense that it is-made up of small particles. The amount of solvent added is not su'illcient to dissolve completely all of the particles of the granular plastic, but merely acts upon the surface of the particles, so that adjacent particles-may become'fused'together. The solvent used is one.

that may evaporate sufliciently readily sothat the particles do not have time to become completely dissolved, but, at the' same time, is one that will enable the particles tov be bound together to form a solidmass. The ultimate productibefore application ofv the' surface process will ,have a surface texture moreor less irregular and porous with interstices between adjacent During the application of heat, the surface is fused or melted to some extent without being def stroyed. The principal variables of the heat application are time andlinte'nsity of the heat. These-are adiustedso that the destruction does not occur. Ideally, the process'comprises application of intense heat for a short period. An

optical inspection is sufllcient to cohtrolthisr,

(The plastic material employed is, therefore, one that is granular atthe start and one which is subject to partial dissolving in a suitable solvent. It is likewise one that, having been molded with i a suitable solvent, is subject to. the fusing action at the surface upon the application of heat, so

have an opaque or whitish appearance. whereas 15 that the surface texture may be altered from the and lesser melted or I eifect, without controlled application aids in the fusing action, and comprises a flame carrying medium when the heat is applied by a flame.

Thus the mentioned plastics and solvent are intended to be merely illustrative. The facts of granularity, solubility, capacity for slow burning, and fusibility as characteristics of plastic materials are all plastic power, volatility, vents are qualities known for all solvents. Knowing the desired qualities, the process of this application itself becomes more a mechanical process than a chemical one.

In short, knowing the properties of individual plastic materials and individual solvents, the process may be employed to give the desired surface coloration and texture without experimentation. The surface resulting also will have an materiaL- Likewise, the dissolving increased resistance to further burning and an increased resistance to greater hardness.

The effect of the process is to, produce a surface materially altering internal parts of the material, and this is accomplished by a of heat to determined part wear which may be termed of the surface.

What is claimed is: 1. In a process of producing surface effects on plastic material, the. steps of providing a lower or first piece of plastic material of one color, annexing thereto an upper or second piece of translucent plastic material of different color, said. secafter hea't-treating the irregular outer the second piece of plastic material to cause at least a part of said treated surface to lose at least part of its translucency, and to attain a color in contrast with that of the untreated portion, with the result that the color of the lower or first piece of plastic shows through with varying intensity determined by the degree of translucency at each point on the treated upper or first tic, and thereafter stopping said heat treatment. I 2. The process .of producing surface effects a dye and an inflammable solvent, providing an on said material having portions in relief and decliv'itles among said portions in relief, burning the ble materials upon and the inflammability of sol-.

piece of plasthe surface of said portions in relief and to cause them to change in color, while restricting the burning within the declivities, and checking the burning before destruction of the plastic material of said surface.

3. The process of producing a fused surface on a piece of plastic material of generally crystalline nature, including the steps of applying to said plastic material at the location of said desired surface an inflammable material, causing said material to burn until said surface has fused,

. and stopping said burning prior to disintegration well known in the .art as applied to article having the basic color in of the material at said surface.

4. The process of producing plastic material having contrasting surface effects, comprising the steps of providing a piece of translucent plastic material having opposed surfaces, providing on one opposite surface demarcations, also providing on said surface an inflammable material, causing burning of said while restricting the burning away from the demarcations and away from the other side, and checking the burning after the portion being burned has been caused to lose at least part of its translucency.

5. The process of producing color effects on plastic material, comprising producing a piece of plastic material of desired basic color subject to change in color upon application of heat, providing an irregular surface thereon having indentations and relief portions, app ying heat only to the portions in relief until the surfaces of said relief portions have changed color, to obtain an the indentations and the changed color on the relief portions.

6. The process of plastic material, comprising producing a piece of plastic material of desired basic color and subject to change in colorv 40 heat, producing a surface area thereon having including the steps of pro-,

indentations and relief portions, applying. a flame to said surface portion to effect color change on the relief portions, while limiting and controlling the application of said flame to preventsuch changes in said indentations.

7. The process of producing plastic articles including producing a plastic piece of material subject to change in color effect upon application of heat thereto, providing a surface thereon hav-.

tom portions.

JOHN G. BOYD.

indentations remain substaninilammable material.

producing color effects on' quality upon application of and the portions therebetween 

